Expandable Fusion Device and Method of Installation Thereof

ABSTRACT

The present invention provides an expandable fusion device capable of being installed inside an intervertebral disc space to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. In one embodiment, the fusion device includes a body portion, a first endplate, and a second endplate, the first and second endplates capable of being moved in a direction away from the body portion into an expanded configuration or capable of being moved towards the body portion into an unexpanded configuration. The fusion device is capable of being deployed and installed in both configurations.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 13/273,994, filed on Oct. 14, 2011, which is acontinuation of U.S. patent application Ser. No. 12/579,833, filed onOct. 15, 2009, issued as U.S. Pat. No. 8,062,375 on Nov. 22, 2011, andthe present application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/823,736, filed on Jun. 25, 2010, the entirecontents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the apparatus and method for promotingan intervertebral fusion, and more particularly relates to an expandablefusion device capable of being inserted between adjacent vertebrae tofacilitate the fusion process.

BACKGROUND OF THE INVENTION

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc is first partially or fullyremoved. An intervertebral fusion device is then typically insertedbetween neighboring vertebrae to maintain normal disc spacing andrestore spinal stability, thereby facilitating an intervertebral fusion.

There are a number of known conventional fusion devices andmethodologies in the art for accomplishing the intervertebral fusion.These include screw and rod arrangements, solid bone implants, andfusion devices which include a cage or other implant mechanism which,typically, is packed with bone and/or bone growth inducing substances.These devices are implanted between adjacent vertebral bodies in orderto fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventionalfusion devices and methodologies. For example, present methods forinstalling a conventional fusion device often require that the adjacentvertebral bodies be distracted to restore a diseased disc space to itsnormal or healthy height prior to implantation of the fusion device. Inorder to maintain this height once the fusion device is inserted, thefusion device is usually dimensioned larger in height than the initialdistraction height. This difference in height can make it difficult fora surgeon to install the fusion device in the distracted intervertebralspace.

As such, there exists a need for a fusion device capable of beinginstalled inside an intervertebral disc space at a minimum to nodistraction height and for a fusion device that can maintain a normaldistance between adjacent vertebral bodies when implanted.

SUMMARY OF THE INVENTION

In an exemplary embodiment, the present invention provides an expandablefusion device capable of being installed inside an intervertebral discspace to maintain normal disc spacing and restore spinal stability,thereby facilitating an intervertebral fusion. In one embodiment, thefusion device includes a body portion, a first endplate, and a secondendplate. The first and second endplates are capable of being moved in adirection away from the body portion into an expanded configuration orcapable of being moved towards the body portion into an unexpandedconfiguration. The expandable fusion device is capable of being deployedand installed in the unexpanded configuration or the expandedconfiguration.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred or exemplary embodiments of the invention, areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a side view of an embodiment of an expandable fusion deviceshown between adjacent vertebrae according to the present invention;

FIG. 2 is an exploded view of the expandable fusion device of FIG. 1;

FIG. 3 is a front perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position

FIG. 4 is a front perspective view of the expandable fusion device ofFIG. 1 shown in an expanded position;

FIG. 5 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position;

FIG. 6 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an expanded position;

FIG. 7 is a side view of the expandable fusion device of FIG. 1 shown inan unexpanded position;

FIG. 8 is a side view of the expandable fusion device of FIG. 1 shown inan expanded position;

FIG. 9 is a top view of the expandable fusion device of FIG. 1;

FIG. 10. is a side partial cross-sectional view of the expandable fusiondevice of FIG. 1 shown in an unexpanded position;

FIG. 11 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 1 shown in an expanded position;

FIG. 12 is a side schematic view of the expandable fusion device of FIG.1 having different endplates;

FIG. 13 is a partial side schematic view of the expandable fusion deviceof FIG. 1 showing different modes of endplate expansion; and

FIG. 14 is a side schematic view of the expandable fusion device of FIG.1 with artificial endplates shown between adjacent vertebrae.

FIG. 15 is an exploded view of an alternative embodiment of anexpandable fusion according to the present invention;

FIG. 16 is a rear perspective view of the expandable fusion device ofFIG. 15 shown in an unexpanded position;

FIG. 17 is a side cross-sectional view of the expandable fusion deviceof FIG. 15 shown with one of the endplates removed;

FIG. 18 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 15 shown in an unexpanded position;

FIG. 19 is a side partial cross-sectional view of the expandable fusiondevice of FIG. 15 shown in an expanded position;

FIG. 20 is a side view cross-sectional view of another embodiment of anexpandable fusion device shown in an unexpanded position;

FIG. 21 is a side view cross-sectional view of the expandable fusiondevice of FIG. 20 shown in an expanded position;

FIG. 22 is a side view of the expandable fusion device of FIG. 20showing the translation member and the ramped insert;

FIG. 23 is a front perspective view of the expandable fusion device ofFIG. 20 showing the translation member and the ramped insert;

FIG. 24 is a rear perspective of another embodiment of an expandablefusion device with the endplates having a threaded hole;

FIG. 25 is a top view of another embodiment of an expandable fusiondevice shown in an unexpanded position;

FIG. 26 is a bottom view of the expandable fusion device of FIG. 25;

FIG. 27 is top view of the expandable fusion device of FIG. 25 shown inan expanded position;

FIG. 28 is an exploded perspective view of another embodiment of anexpandable fusion device;

FIG. 29 is an end view of the expandable fusion device of FIG. 28 in anunexpanded position;

FIG. 30 is an end view of the expandable fusion device of FIG. 28 in anexpanded position;

FIG. 31 is a perspective view of another embodiment of an expandablefusion device;

FIG. 32 is a top view of the expandable fusion device of FIG. 31;

FIG. 33 is a perspective view of the expandable fusion device of FIG. 31with a closed end;

FIG. 34 is a front view of the expandable fusion device of FIG. 33 shownbetween adjacent vertebrae in an unexpanded position;

FIG. 35 is a front view of the expandable fusion device of FIG. 33 shownbetween adjacent vertebrae in an expanded position;

FIG. 36 is an exploded view of another embodiment of an expandablefusion device according to the present invention;

FIG. 37 is a front perspective of the expandable fusion device of FIG.36;

FIG. 38 is a side view of the expandable fusion device of FIG. 36 in anunexpanded configuration;

FIG. 39 is a cross-sectional side view of the expandable fusion deviceof FIG. 36 in an unexpanded configuration;

FIG. 40 is a side view of the expandable fusion device of FIG. 36 in anexpanded configuration;

FIG. 41 is a cross-sectional side view of the expandable fusion deviceof FIG. 36 in an expanded configuration;

FIG. 42 is a cross-sectional side view of the expandable member of theexpandable fusion device of FIG. 36;

FIG. 43 is a front perspective of the body portion of the expandablefusion device of FIG. 36;

FIG. 44 is a cross-sectional side view of an alternative embodiment ofthe expandable fusion device of FIG. 36 in an unexpanded configuration;

FIG. 45 is a cross-sectional side view of the alternative embodiment ofthe expandable fusion device shown on FIG. 44;

FIG. 46 is a cross-sectional side view of an alternative embodiment ofthe expandable fusion device of FIG. 36 in an unexpanded configuration;and

FIGS. 47-58 are side views of an expandable fusion device showingdifferent modes of lordotic expansion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disk material. Upon successful fusion, a fusiondevice becomes permanently fixed within the intervertebral disc space.Looking at FIG. 1, an exemplary embodiment of an expandable fusiondevice 10 is shown between adjacent vertebral bodies 2 and 3. The fusiondevice 10 engages the endplates 4 and 5 of the adjacent vertebral bodies2 and 3 and, in the installed position, maintains normal intervertebraldisc spacing and restores spinal stability, thereby facilitating anintervertebral fusion. The expandable fusion device 10 can bemanufactured from a number of materials including titanium, stainlesssteel, titanium alloys, non-titanium metallic alloys, polymericmaterials, plastics, plastic composites, PEEK, ceramic, and elasticmaterials.

In an exemplary embodiment, bone graft or similar bone growth inducingmaterial can be introduced around and within the fusion device 10 tofurther promote and facilitate the intervertebral fusion. The fusiondevice 10, in one embodiment, is preferably packed with bone graft orsimilar bone growth inducing material to promote the growth of bonethrough and around the fusion device. Such bone graft may be packedbetween the endplates of the adjacent vertebral bodies prior to,subsequent to, or during implantation of the fusion device.

With reference to FIG. 2, an exploded perspective view of one embodimentof the fusion device 10 is shown. In an exemplary embodiment, the fusiondevice 10 includes a body portion 12, a first endplate 14, a secondendplate 16, a translation member 18, a plurality of pins 20, anactuation member 22, and a locking mechanism 24.

With additional reference to FIGS. 3-8, in an exemplary embodiment, thebody portion 12 has a first end 26, a second end 28, a first sideportion 30 connecting the first end 26 and the second end 28, and asecond side portion 32 connecting the first end 26 and the second end28. The body portion 12 further includes an upper end 34, which is sizedto receive at least a portion of the first endplate 14, and a lower end36, which is sized to receive at least a portion of the second endplate16.

The first end 26 of the fusion device 10, in an exemplary embodiment,includes at least one angled surface 38, but can include multiple angledsurfaces. The angled surface can serve to distract the adjacentvertebral bodies when the fusion device 10 is inserted into anintervertebral space. In another preferred embodiment, it iscontemplated that there are at least two opposing angled surfacesforming a generally wedge shaped to distract the adjacent vertebralbodies when the fusion device 10 is inserted into an intervertebralspace.

The second end 28 of the body portion 12, in an exemplary embodiment,includes an opening 40 which may include threading. In another exemplaryembodiment, the opening 40 may include ratchet teeth instead ofthreading. The opening 40 extends from the second end 28 of the bodyportion 12 into a central opening 42 in the body portion 12. In oneembodiment, the central opening 42 is sized to receive the translationmember 18 and the opening 40 is sized to threadingly receive theactuation member 22. In another exemplary embodiment, the opening 40 issized to receive the actuation member 22 in a ratcheting fashion. In yetanother exemplary embodiment, first side portion 30 and second sideportion 32 each include a recess 44 located towards the second end 28 ofthe body portion 12. The recess 44 is configured and dimensioned toreceive an insertion instrument (not shown) that assists in theinsertion of the fusion device 10 into an intervertebral space.

Although the following discussion relates to the first endplate 14, itshould be understood that it also equally applies to the second endplate16 as the second endplate 16 is substantially identical to the firstendplate 14. Turning now to FIGS. 2-11, in an exemplary embodiment, thefirst endplate 14 has an upper surface 46, a lower surface 48, and athrough opening 49. The through opening 49, in an exemplary embodiment,is sized to receive bone graft or similar bone growth inducing materialand further allow the bone graft or similar bone growth inducingmaterial to be packed in the central opening 42 in the body portion 12.

In one embodiment, the lower surface 48 includes at least one extension50 extending along at least a portion of the lower surface 48. As bestseen in FIGS. 2 and 4, in an exemplary embodiment, the extension 50 canextend along a substantial portion of the lower surface 48, including,along each side of the endplate 14 and along the front end of theendplate 14. In another exemplary embodiment, the extension 50 includesat least one slot 52, but can include any number of slots 52, includingtwo sets of slots 52 opposing each other, as best seen in FIG. 2. Theslots 52 are configured and dimensioned to receive pins 20 and areoriented in an oblique fashion. In another embodiment, the slots 52 maybe oriented in a generally vertical orientation.

In an exemplary embodiment, the extension 50 is sized to be receivedwithin the central opening 42 of the body portion 12. As best seen inFIGS. 11-12, the lower surface 48 of the first endplate 14 furtherincludes, in an exemplary embodiment, at least one ramped surface 54. Inanother exemplary embodiment, there are two spaced ramped surfaces 54,56. It is contemplated that the slope of the ramped surfaces 54, 56 canbe equal or can differ from each other. The effect of varying the slopesof the ramped surfaces 54, 56 is discussed below.

Referring now to FIGS. 2-9, in one embodiment, the upper surface 46 ofthe first endplate 14 is flat and generally planar to allow the uppersurface 46 of the endplate 14 to engage with the adjacent vertebral body2. Alternatively, as shown in FIG. 12, the upper surface 46 can becurved convexly or concavely to allow for a greater or lesser degree ofengagement with the adjacent vertebral body 2. It is also contemplatedthat the upper surface 46 can be generally planar but includes agenerally straight ramped surface or a curved ramped surface. The rampedsurface allows for engagement with the adjacent vertebral body 2 in alordotic fashion. Turning back to FIGS. 2-9, in an exemplary embodiment,the upper surface 46 includes texturing 58 to aid in gripping theadjacent vertebral bodies. Although not limited to the following, thetexturing can include teeth, ridges, friction increasing elements,keels, or gripping or purchasing projections.

With reference to FIGS. 2 and 10-11, in an exemplary embodiment, thetranslation member 18 is sized to be received within the central opening42 of the body portion 12 and includes at least a first expansionportion 60. In another embodiment, the translation member 18 includes afirst expansion portion 60 and a second expansion portion 62, theexpansion portions 60, 62 being connected together via a bridge portion68. It is also contemplated that there may be more than two expansionportions where each of the expansion portions is connected by a bridgeportion. The expansion portions 60, 62 each have angled surfaces 64, 66configured and dimensioned to engage the ramp surfaces 54, 56 of thefirst and second endplates 14, 16. In an exemplary embodiment, thetranslation member 18 also includes recesses 70, 72, the recesses 70, 72are sized to receive and retain pins 20. In one embodiment, theexpansion portion 60 includes an opening 74, which is sized to receive aportion of the actuation member 22, and the expansion portion 62includes a nose 76, which is received within an opening 78 in the firstend 26 to stabilize the translation member 18 in the central opening 42of the body member 12.

In an exemplary embodiment, the actuation member 22 has a first end 80,a second end 82 and threading 84 extending along at least a portionthereof from the first end 80 to the second end 82. The threading 84threadingly engages the threading extending along a portion of opening40 in the body portion 12. In another exemplary embodiment, theactuation member 22 includes ratchet teeth instead of threading. Theratchet teeth engage corresponding ratchet teeth in the opening 40 inthe body portion 12. The first end 80 includes a recess 86 dimensionedto receive an instrument (not shown) that is capable of advancing theactuation member 22 with respect to the body portion 12 of the fusiondevice 10. The second end 82 of the actuation member 22 includes anextension 88 that is received within the opening 74 of the expansionportion 60. In one embodiment, the extension 88 may include a pluralityof slits and a lip portion. The plurality of slits allows the extensionportion 88 to flex inwardly reducing its diameter when received in theopening 74. Once the lip portion of the extension portion 88 is advancedbeyond the end of the opening 74, the extension portion 88 will returnback to its original diameter and the lip portion will engage theexpansion portion 60. It is further contemplated that a pin member 90can be included to prevent the extension portion from flexing inwardlythereby preventing the actuation member 22 from disengaging from thetranslation member 18.

In an exemplary embodiment, the fusion device 10 can further include alocking mechanism 24. The mechanism 24 is designed to resist rotation ofthe actuation member 22 rather than prevent rotation of the actuationmember 22. In an exemplary embodiment, either deformable threading canbe included on actuation member 22 or a disruption of the threading maybe included where a deformable material is included in the threadingdisruption. It is contemplated that the deformable member or deformablethreading can be made from a deformable or elastic, biocompatiblematerial such as nitinol or PEEK.

Turning now to FIGS. 1-8 and 10-11, an example method of installing theexpandable fusion device 10 is now discussed. Prior to insertion of thefusion device 10, the intervertebral space is prepared. In one method ofinstallation, a diskectomy is performed where the intervertebral disc,in its entirety, is removed. Alternatively, only a portion of theintervertebral disc can be removed. The endplates of the adjacentvertebral bodies 2, 3 are then scraped to create an exposed end surfacefor facilitating bone growth across the intervertebral space. Theexpandable fusion device 10 is then introduced into the intervertebralspace, with the first end 26 being inserted first into the disc spacefollowed by the second end 28. In an exemplary method, the fusion device10 is in the unexpanded position when introduced into the intervertebralspace. The wedged shaped first end 26 will assist in distracting theadjacent vertebral bodies 2, 3 if necessary. This allows for the optionof having little to no distraction of the intervertebral space prior tothe insertion of the fusion device 10. In another exemplary method, theintervertebral space may be distracted prior to insertion of the fusiondevice 10. The distraction provide some benefits by providing greateraccess to the surgical site making removal of the intervertebral disceasier and making scraping of the endplates of the vertebral bodies 2, 3easier.

With the fusion device 10 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can thenexpanded into the expanded position, as best seen in FIGS. 1, 4, 6, 8,and 11. To expand the fusion device 10, an instrument is engaged withrecess 86 in the actuation member 22. The instrument is used to rotateactuation member 22. As discussed above, actuation member 22 isthreadingly engaged body portion 12 and is engaged with translationmember 18; thus, as the actuation member 22 is rotated in a firstdirection, the actuation member 22 and the translation member 18 movewith respect to the body portion 12 toward the first end 26 of the bodyportion 12. In another exemplary embodiment, the actuation member 22 ismoved in a linear direction with the ratchet teeth engaging as means forcontrolling the movement of the actuation member 22 and the translationmember 18. As the translation member 18 moves, the ramped surface 64, 66of the expansion portions 60, 62 push against the ramped surfaces 54, 56of the endplates 14, 16 pushing endplates 14, 16 outwardly into theexpanded position. This can best be seen in FIGS. 10 and 11. Since theexpansion of the fusion device 10 is actuated by a rotational input, theexpansion of the fusion device 10 is infinite. In other words, theendplates 14, 16 can be expanded to an infinite number of heightsdependent on the rotational advancement of the actuation member 22. Asdiscussed above, the fusion device 10 includes a locking mechanism 24which assists in retaining the endplates 14, 16 at the desired height.

It should also be noted that the expansion of the endplates 14, 16 canbe varied based on the differences in the dimensions of the rampedsurfaces 54, 56, 64, 66. As best seen in FIG. 13, the endplates 14, 16can be expanded in any of the following ways: straight rise expansion,straight rise expansion followed by a toggle into a lordotic expandedconfiguration, or a phase off straight rise into a lordotic expandedconfiguration.

Turning back to FIGS. 1-8 and 10-11, in the event the fusion device 10needs to be repositioned or revised after being installed and expanded,the fusion device 10 can be contracted back to the unexpandedconfiguration, repositioned, and expanded again once the desiredpositioning is achieved. To contract the fusion device 10, theinstrument is engaged with recess 86 in the actuation member 22. Theinstrument is used to rotate actuation member 22. As discussed above,actuation member 22 is threadingly engaged body portion 12 and isengaged with translation member 18; thus, as the actuation member 22 isrotated in a second direction, opposite the first direction, theactuation member 22 and translation member 18 move with respect to thebody portion 12 toward the second end 28 of the body portion 12. As thetranslation member 18 moves, the pins 20, a portion of which are locatedwithin the slots 52, ride along the slots 52 pulling the endplates 14,16 inwardly into the unexpanded position.

With reference now to FIG. 14, fusion device 10 is shown with anexemplary embodiment of artificial endplates 100. Artificial endplates100 allows the introduction of lordosis even when the endplates 14 and16 of the fusion device 10 are generally planar. In one embodiment, theartificial endplates 100 have an upper surface 102 and a lower surface104. The upper surfaces 102 of the artificial endplates 100 have atleast one spike 106 to engage the adjacent vertebral bodies. The lowersurfaces 104 have complementary texturing or engagement features ontheir surfaces to engage with the texturing or engagement features onthe upper endplate 14 and the lower endplate 16 of the fusion device 10.In an exemplary embodiment, the upper surface 102 of the artificialendplates 100 have a generally convex profile and the lower surfaces 104have a generally parallel profile to achieve lordosis. In anotherexemplary embodiment, fusion device 10 can be used with only oneartificial endplate 100 to introduce lordosis even when the endplates 14and 16 of the fusion device 10 are generally planar. The artificialendplate 100 can either engage endplate 14 or engage endplate 16 andfunction in the same manner as described above with respect to twoartificial endplates 100.

With reference to FIG. 15, an exploded perspective view of alternativeembodiment of a fusion device 210 is shown. In an exemplary embodiment,the fusion device 210 includes a body portion 212, a first endplate 214,a second endplate 216, a translation member 218, an actuation member220, and an insert 222.

With additional reference to FIGS. 16-19, in an exemplary embodiment,the body portion 212 has a first end 224, a second end 226, a first sideportion 228 connecting the first end 224 and the second end 226, and asecond side portion 229 on the opposing side of the body portion 212connecting the first end 224 and the second end 226. The body portion212 further includes an upper end 230, which is sized to receive atleast a portion of the first endplate 214, and a lower end 232, which issized to receive at least a portion of the second endplate 216.

The first end 224 of the body portion 212, in an exemplary embodiment,includes at least one angled surface 234, but can include multipleangled surfaces. The angled surface 234 can serve to distract theadjacent vertebral bodies when the fusion device 210 is inserted into anintervertebral space. In another preferred embodiment, it iscontemplated that there are at least two opposing angled surfacesforming a generally wedge shaped to distract the adjacent vertebralbodies when the fusion device 210 is inserted into an intervertebralspace.

The second end 226 of the body portion 212, in an exemplary embodiment,includes an opening 236 which may include threading. In anotherexemplary embodiment, the opening 236 may include ratchet teeth insteadof threading. The opening 236 extends from the second end 226 of thebody portion 212 into a central opening (not illustrated) in the bodyportion 212. In one embodiment, the central opening is sized to receivethe translation member 218, and the opening 236 is sized to threadinglyreceive the actuation member 220. In another exemplary embodiment, theopening 236 is sized to receive the actuation member 220 in a ratchetingfashion. In yet another exemplary embodiment, first side portion 228 andsecond side portion 229 each include a recess 238 located towards thesecond end 226 of the body portion 212. The recess 238 is configured anddimensioned to receive an insertion instrument (not shown) that assistsin the insertion of the fusion device 210 into an intervertebral space.

Although the following discussion relates to the first endplate 214, itshould be understood that it also equally applies to the second endplate216 as the second endplate 216 is substantially identical to the firstendplate 214 in embodiments of the present invention. Turning now toFIGS. 15-19, in an exemplary embodiment, the first endplate 214 has anupper surface 240, a lower surface 242, and a through opening 243. Thethrough opening 243, in an exemplary embodiment, is sized to receivebone graft or similar bone growth inducing material and further allowthe bone graft or similar bone growth inducing material to be packed inthe central opening in the body portion 212.

In one embodiment, the lower surface 242 includes at least one extension244 extending along at least a portion of the lower surface 242. As bestseen in FIGS. 16 and 17, in an exemplary embodiment, the extension 244can extend along a substantial portion of the lower surface 242,including, along each side of the endplate 214 and along the front endof the endplate 214. In another exemplary embodiment, the extension 244includes at least one ramped portion 246, but can include any number oframped portions, including two spaced ramped portions 246, 248 in theextension 244 that extend between each side of the endplate 214, as bestseen in FIG. 17. It is contemplated that the slope of the rampedportions 246, 248 can be equal or can differ from each other. The effectof varying the slopes of the ramped portions 246, 248 is discussedbelow.

In an exemplary embodiment, the ramped portions 246, 248 further includegrooved portions 247, 249 that are configured and dimensioned to receiveangled surfaces 258, 260 of the translation member 218 and are orientedin an oblique fashion. In a preferred embodiment, the grooved portions246, 248 are dovetail grooves configured and dimensioned to hold theangled surfaces 258, 260 of the translation member 218 while allowingthe angles surfaces 258, 260 to slide against the ramped portions 246,248.

Referring now to FIGS. 16-19, in one embodiment, the upper surface 240of the first endplate 214 is flat and generally planar to allow theupper surface 240 of the endplate 214 to engage with the adjacentvertebral body 2 (e.g., shown on FIG. 1). Alternatively, as shown in theupper surface 240 can be curved convexly or concavely to allow for agreater or lesser degree of engagement with the adjacent vertebral body2, as shown on FIG. 12 with respect to fusion device 10, for example. Itis also contemplated that the upper surface 240 can be generally planarbut includes a generally straight ramped surface or a curved rampedsurface. The ramped surface allows for engagement with the adjacentvertebral body 2 in a lordotic fashion. Turning back to FIGS. 15-19, inan exemplary embodiment, the upper surface 240 includes texturing 250 toaid in gripping the adjacent vertebral bodies. Although not limited tothe following, the texturing can include teeth, ridges, frictionincreasing elements, keels, or gripping or purchasing projections.

With reference to FIGS. 15 and 17-19, in an exemplary embodiment, thetranslation member 218 is sized to be received within the centralopening of the body portion 212 and includes at least a first expansionportion 252. In another embodiment, the translation member 218 includesa first expansion portion 252 and a second expansion portion 254, theexpansion portions 252, 254 being connected together via a bridgeportion 256. It is also contemplated that there may be more than twoexpansion portions where each of the expansion portions is connected bya bridge portion. The expansion portions 252, 254 each have angledsurfaces 258, 260 configured and dimensioned to engage the groovedportions 246, 248 of the first and second endplates 214, 216. In oneembodiment, the translation member 218 includes an opening 262 in thefirst expansion portion 252, which is sized to receive a portion of theactuation member 220, as best seen in FIG. 17. In an exemplaryembodiment, the first expansion portion 252 includes a central bore 263that extends from the opening 262 and through the first expansionportion 252. In one embodiment, the translation member 218 includes ahole 264 in the second expansion portion 254, which is sized to receivenose 266, as best seen in FIGS. 18 and 19. In an exemplary embodiment,the hole 264 includes threading 268 for threadedly receiving a threadedend 270 of the nose 266, as shown on FIG. 19. The nose 266 is receivedin an opening 272 in the first end 234 of the body portion 212 tostabilize the translation member 218 in the central opening of the bodyportion 212.

In one embodiment, the translation member 218 includes a lockingmechanism 274, which is configured and adapted to engage the actuationmember 220. As illustrated, the locking mechanism 274 may extend fromthe first expansion portion 252. The locking mechanism 274 includes aslot 276 configured and adapted to receive extension 287 of theactuation member 220. In an exemplary embodiment, the locking mechanism274 further includes a stop 278 (e.g., a rim, a lip, etc.) that engagesthe actuation member 220 when it is disposed in the slot 276.

Referring now to FIGS. 15-19, in an exemplary embodiment, the actuationmember 220 has a first end 280, a second end 282, and threading (notillustrated) extending along at least a portion thereof from the firstend 280 to the second end 282. The threading threadingly engages thethreading that extends along a portion of opening 236 in the bodyportion 212. In another exemplary embodiment, the actuation member 220includes ratchet teeth instead of threading. The ratchet teeth engagecorresponding ratchet teeth in the opening 236 in the body portion 212.The first end 280 includes a recess 284 dimensioned to receive aninstrument (not shown) that is capable of advancing the actuation member220 with respect to the body portion 212 of the fusion device 210. In anembodiment, the actuation member 220 includes a bore 285, as best seenby FIG. 17, that extends from the recess 284 in the first end to thesecond 282. The second end 282 of the actuation member 220 includes anextension 286 that is received within the opening 262 in the firstexpansion portion 252. In one embodiment, the extension 288 may includea lip portion 286 and a plurality of slits 288. The plurality of slits288 are configured to receive inserts 222. Inserts 222 are provided tolimit motion of the actuation member 220. Once the lip portion 286 isplaced into the slot 276 of the locking mechanism 274, the lip portion286 will engage the stop 278 preventing longitudinal movement of theactuation member 220 with respect to the translation member 218. It isfurther contemplated that a pin member 290 can be included to furthersecure the actuation member 220 in the translation member 218. In anembodiment, the pin member 290 can be pressed into the central bore 285of the actuation member 220 and the central bore 263 of the translationmember, thereby preventing the actuation member 220 from disengagingfrom the translation member 218. Additionally, in an exemplaryembodiment, the fusion device 210 can further include a chamfered tip224 for distraction of adjacent vertebrae.

Turning now to FIGS. 2-19, an example method of installing theexpandable fusion device 210 is now discussed. Prior to insertion of thefusion device 210, the intervertebral space is prepared. In one methodof installation, a diskectomy is performed where the intervertebraldisc, in its entirety, is removed. Alternatively, only a portion of theintervertebral disc can be removed. The endplates of the adjacentvertebral bodies 2, 3 (shown on FIG. 1, for example) are then scraped tocreate an exposed end surface for facilitating bone growth across theintervertebral space. The expandable fusion device 210 is thenintroduced into the intervertebral space, with the first end 222 of thebody portion 212 being inserted first into the disc space followed bythe second end 224. In an exemplary method, the fusion device 210 is inthe unexpanded position when introduced into the intervertebral space.The wedged-shaped first end 222 should assist in distracting theadjacent vertebral bodies 2, 3, if necessary. This allows for the optionof having little to no distraction of the intervertebral space prior tothe insertion of the fusion device 210. In another exemplary method, theintervertebral space may be distracted prior to insertion of the fusiondevice 210. The distraction provide some benefits by providing greateraccess to the surgical site making removal of the intervertebral disceasier and making scraping of the endplates of the vertebral bodies 2, 3easier.

With the fusion device 210 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can thenexpanded into the expanded position, as best seen in FIGS. 18 and 19, Toexpand the fusion device 210, an instrument is engaged with recess 284in the actuation member 220. The instrument is used to rotate actuationmember 220. As discussed above, actuation member 220 can be threadinglyengaging body portion 212 and is engaged with translation member 218;thus, as the actuation member 220 is rotated in a first direction, theactuation member 220 and the translation member 218 move with respect tothe body portion 212 toward the first end 222 of the body portion 212.In another exemplary embodiment, the actuation member 220 is moved in alinear direction with the ratchet teeth engaging as means forcontrolling the movement of the actuation member 220 and the translationmember 218. As the translation member 218 moves, the angled surfaces258, 260 of the expansion portions 252, 254 push against the rampedportions 246, 248 of the endplates 214, 216 pushing endplates 214, 216outwardly into the expanded position with the angled surfaces 258, 260riding along the grooved portions 247, 248 of the ramped portions 246,248. This can best be seen in FIGS. 18 and 19. Since the expansion ofthe fusion device 210 is actuated by a rotational input, the expansionof the fusion device 210 is infinite. In other words, the endplates 214,216 can be expanded to an infinite number of heights dependent on therotational advancement of the actuation member 220. As discussed above,the fusion device 210 includes a locking mechanism 222 which assists inretaining the endplates 214, 216 at the desired height.

It should also be noted that the expansion of the endplates 214,216 canbe varied based on the differences in the dimensions of the rampedportions 246, 248 and the angled surfaces 258, 260. For example, theendplates 214, 216 can be expanded in any of the following ways:straight rise expansion, straight rise expansion followed by a toggleinto a lordotic expanded configuration, or a phase off straight riseinto a lordotic expanded configuration, which are discussed above withrespect to FIG. 13 for fusion device 10.

Turning back to FIGS. 15-19, in the event the fusion device 210 needs tobe repositioned or revised after being installed and expanded, thefusion device 210 can be contracted back to the unexpandedconfiguration, repositioned, and expanded again once the desiredpositioning is achieved. To contract the fusion device 210, theinstrument is engaged with recess 284 in the actuation member 220. Theinstrument is used to rotate actuation member 220. As discussed above,actuation member 220 can be threadingly engaging body portion 212 and isengaged with translation member 218; thus, as the actuation member 220is rotated in a second direction, opposite the first direction, theactuation member 220 and translation member 218 move with respect to thebody portion 212 toward the second end 226 of the body portion 212. Asthe translation member 218 moves, the angled surfaces 258, 260 of thetranslation member 218 ride along the grooved portions 247, 249 pullingthe endplates 214,216 inwardly into the unexpanded position.

In some embodiments, artificial endplates (e.g., endplates 100 shown onFIG. 14) may be used with fusion device 210. As will be appreciated, theartificial endplates allow the introduction of lordosis even when theendplates 214 and 216 of the fusion device 210 are generally planar.

Referring now to FIGS. 20 and 21, an alternative embodiment of thefusion device 210 is shown. In an exemplary embodiment, the fusiondevice 210 includes a body portion 212, a first endplate 214, a secondendplate 216, a translation member 218, and an actuation member 220. Inthe illustrated embodiment, the fusion device further includes a firstramped insert 320 and a second ramped insert 322.

Although the following discussion relates to the first ramped insert320, it should be understood that it also equally applies to the secondramped insert 322 as the second ramped insert 322 is substantiallyidentical to the first ramped insert 320 in embodiments of the presentinvention. Turning now to FIGS. 20-23, in an exemplary embodiment, thefirst ramped insert 320 includes a first ramped portion 324 and a secondramped portion 326, the first and second ramped portions 324, 326 beingconnected by a bridge portion 328. The ramped portions 324, 326 eachhave grooved portions 330, 332 configured and dimensioned to receiveangled surfaces 258, 260 of the translation member. The ramped portions324, 326 can be oriented in an oblique fashion, as illustrated. In apreferred embodiment, the grooved portions 330, 332 are dovetail groovesconfigured and dimensioned to hold the angled surfaces 258, 260 of thetranslation member 218 while allowing the angles surfaces 258, 260 toslide against the ramped portions 324, 326.

In an exemplary embodiment, the first ramped insert 320 should beconfigured and dimensioned to be engaged with the first endplate 214. Inan embodiment, the first and second ramped portions 324, 326 includesnap connectors 334, 336 for securing the first ramped insert 320 to thefirst endplate. It should be understood that the snap connectors 334,336 are merely illustrative and that other suitable mechanisms forsecuring the first ramped inserted 320 with the first endplate 214 maybe used.

Referring to FIGS. 20-23, in an exemplary embodiment, the translationmember 218 is sized to be received within the central opening of thebody portion 212 and includes at least a first expansion portion 252. Inanother embodiment, the translation member 218 includes a firstexpansion portion 252 and a second expansion portion 254, the expansionportions 252, 254 being connected together via a bridge portion 256. Itis also contemplated that there may be more than two expansion portionswhere each of the expansion portions is connected by a bridge portion.The expansion portions 252, 254 each have angled surfaces 258, 260configured and dimensioned to engage the grooved portions 330, 332 ofthe first and second ramped inserts 320, 322. In one embodiment, theangled surfaces 258, 260 include corresponding grooved portions 338,340, as best seen in FIG. 13, that slidingly engaged the groovedportions 330, 332 of the first and second ramped inserts 320, 322.

In one embodiment, the expansion portion 252 includes an opening 262,which is sized to receive a portion of the actuation member 220, and theexpansion portion 262 includes a nose 266, which is received within anopening 272 in the first end 234 of the body portion 212 to stabilizethe translation member 218 in the central opening of the body portion212. In an embodiment, the nose 266 is integral with the expansionportion 262. In an embodiment (shown on FIGS. 15 and 17-19), the nose266 is threadingly engaged with the expansion portion 262. In anembodiment, the translation member 218 includes a locking mechanism 274to engage the actuation member 220, as illustrated in FIGS. 15-19.However, it should be understood that other suitable mechanisms may beused to secure the actuation member 220 within the translation member218. For example, the actuation member 220 may include an extension 287having a lip portion 286 (shown on FIGS. 15 and 17-19) that engages theexpansion portion 262. The extension 287 may, for example, be configuredto flex inwardly reducing its diameter when received in the opening 262.Once the lip portion 286 of the extension 287 is advanced beyond the endof the opening 262, the extension portion 287 will return back to itsoriginal diameter and the lip portion 286 will engage the expansionportion 260.

The expandable fusion device 210 of FIGS. 20-23 can be inserted into theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 15-19. After insertion, the expandablefusion device 210 of FIGS. 20-23 can be expanded into the expandedposition, as best seen in FIGS. 20 and 21. To expand the fusion device210, an instrument is engaged with recess 284 in the actuation member220. The instrument is used to rotate actuation member 220. As discussedabove, actuation member 220 can be threadingly engaging body portion 212and is engaged with translation member 218; thus, as the actuationmember 220 is rotated in a first direction, the actuation member 220 andthe translation member 218 move with respect to the body portion 212toward the first end 222 of the body portion 212. In another exemplaryembodiment, the actuation member 220 is moved in a linear direction withthe ratchet teeth engaging as means for controlling the movement of theactuation member 220 and the translation member 218. As the translationmember 218 moves, the angled surfaces 258, 260 of the expansion portions252, 254 push against the ramped portions 324, 326 of the first andsecond ramped inserts 320, 322 while riding along the grooved portions330, 332, thus pushing first and second ramped inserts 320, 322outwardly. Because the first and second ramped inserts 320, 322 areengaged with the endplates 214, 216, the endplates 214, 216 are alsopushed outwardly into the expanded position.

After expansion, the expandable fusion device 210 can be contracted backto the unexpanded configuration. To contract the fusion device 210, theinstrument is engaged with recess 284 in the actuation member 220. Theinstrument is used to rotate actuation member 220. As discussed above,actuation member 220 can be threadingly engaging body portion 212 and isengaged with translation member 218; thus, as the actuation member 220is rotated in a second direction, opposite the first direction, theactuation member 220 and translation member 218 move with respect to thebody portion 212 toward the second end 226 of the body portion 212. Asthe translation member 218 moves, the angled surfaces 258, 260 of thetranslation member 218 ride along the grooved portions 330, 332 pullingthe first and second ramped inserts 320,322 and thus, the endplates 214,216 inwardly into the unexpanded position.

Referring now to FIG. 24, an alternative embodiment of the fusion device210 is shown. In an exemplary embodiment, the first endplate 214 and thesecond endplate 216 each include additional geometry to help securelyhold the endplates 214,216 in place. In an embodiment, the firstendplate 214 and/or the second endplate 216 include threaded holes 341through which the fasteners, such as screws 342, may be inserted. In anembodiment, the threaded holes 341 penetrate through the first endplate214 and/or the second endplate 216 in an oblique fashion. It iscontemplated that the screws 342 may inserted through the threaded holes341 and into adjacent vertebral bodies 2, 3 (shown on FIG. 1, forexample), to further secure the first endplate 214 and the secondendplate 216 to the vertebral bodies 2, 3. In some embodiments, thesefasteners may be removed once a more long-term interface has beenestablished, or alternatively the fasteners may remain in placeindefinitely or until the fusion device 210 needs adjustment and/orreplacement.

With reference now FIGS. 25-27, an alternative embodiment of the fusiondevice 210 is shown that expands laterally. Lateral expansion maximizescoverage of the intervertebral disc space for wider load distributionand stability providing a rigid foundation for fusion. In oneembodiment, the fusion device 210 includes body portion 212, firstendplate 344, and second endplate 346.

Although the following discussion relates to the first endplate 344, itshould be understood that it also equally applies to the second endplate346 as the second endplate 346 is substantially identical to the firstendplate 344 in embodiments of the present invention. Turning now toFIGS. 25-27, in an exemplary embodiment, the first endplate 344 has anupper surface 348, a lower surface 350, and an inner surface 351 facingthe body portion 312. It is contemplated that the upper surface 2348will engage adjacent vertebral body 2 (seen on FIG. 1, for example) andthe lower surface 350 will engage adjacent vertebral body 3 (seen onFIG. 1, for example). In one embodiment, the upper surface 348 and thelower surface 350 are each flat and generally planar to allow the uppersurface 348 to engage with the adjacent vertebral body 3. Alternatively,the upper surface 348 and/or the lower surface 350 can be curvedconvexly or concavely to allow for a greater or lesser degree ofengagement with the adjacent vertebral bodies 2, 3. It is alsocontemplated that the upper surface 348 and/or the lower surface 350 canbe generally planar but includes a generally straight ramped surface ora curved ramped surface. The ramped surface allows for engagement withthe adjacent vertebral body 2 and/or the adjacent vertebral body 3 in alordotic fashion. In an exemplary embodiment, the upper surface 2348and/or lower surface 350 includes textures 352 to aid in gripping theadjacent vertebral bodies. Although not limited to the following, thetexturing can include teeth, ridges, friction increasing elements,keels, or gripping or purchasing projections.

In one embodiment, the inner surface 351 includes at least one extension354 extending along at least a portion of the inner surface 351. In anexemplary embodiment, the extension 354 can extend along a substantialportion of the inner surface 354, including, along each side of theendplate 344 and along the front end of the endplate 344. While notillustrated, the inner surface may include ramped surfaces and groovedportions in an exemplary embodiment. It is contemplated that the rampedsurfaces and/or grooved portions may be similar to the ramped surfaces246, 248 and grooved portion 247, 249 in extension 344 shown on FIGS.17-19. In an embodiment, the extension 354 may include slots 356oriented in an oblique fashion through which pins 358 may be inserted.

While not illustrated, the fusion device 210 further includes featuresto effectuate the lateral expansion of the first and second endplates344, 346. In one embodiment, the fusion device 210 using a rampingsystem—similar to the system illustrated in FIGS. 15 and 17-19—forexpanding the first and second endplates 344, 346. In an exemplaryembodiment, the fusion device 210 further includes a translation memberand actuation member, such as translation member 218 and actuationmember 220 shown on FIGS. 15 and 17-19. It is contemplated that thetranslation member may include angled surfaces that push against rampedsurfaces in the extension 354, expanding the first and second endplates344, 346 outwardly and away from the body portion 212. In an embodiment,pins 356 disposed through the slots 354 may be retained in thetranslation member. In an alternative embodiment, dovetailing may beused for engagement of the angled surfaces and ramped surfaces. Itshould be understood that the translation member and actuation member inthis embodiment may be similar to the translation member 218 andactuation member 220 described above with respect FIGS. 15-19. Inanother embodiment, the fusion device 210 further includes first andsecond ramped inserts that are secured within the first and secondendplates 344, 346. The first and second ramped inserts may be similarto the first and second ramped inserts 320, 322 described above withrespect to FIGS. 20-23. It is contemplated that angled surfaces in thetranslation member may push against ramped surfaces in the rampedinserts pushing the ramped inserts outwardly. Because of theirengagement with the first and second endplates 344, 346, the first andsecond endplates 344, 346 may thus be expanded outwardly. In thismanner, the first and second endplates 344, 346 may be laterallyexpanded away from the body portion 212. It should be understood thatother suitable techniques may also be used to effectuate this lateralexpansion.

With reference to FIG. 28, an exploded perspective view of anotherembodiment of fusion device 210 is shown. In an exemplary embodiment,the fusion device 210 includes a body portion 212, a first endplate 400,a second endplate 402, a third endplate 404, a fourth endplate 406, anda translation member 218. In this embodiment, the fusion device 210 isconfigured to expand both vertically and laterally.

In an exemplary embodiment, the body portion 212 has a first end 224, asecond end 226, a first side portion 228 connecting the first end 224and the second end 226, and a second side portion 229 on the opposingside of the body portion 212 connecting the first end 224 and the secondend 226. The body portion 212 further includes a top side portion 408connecting the first end 224 and the second end 226, and a bottom sideportion 410 on the opposing side of the body portion 212 connecting thefirst end 224 and the second end 226. The body portion 212 furtherincludes first gap 412 between the top side portion 408 and the firstside portion 228, which is sized to receive at least a portion of thefirst endplate 400. The body portion 212 further includes second gap 414between the top side portion 408 and the second side portion 229, whichis sized to receive at least a portion of the second endplate 402. Thebody portion 212 further includes third gap 416 between the bottom sideportion 410 and the first side portion 228, which is sized to receive atleast a portion of the third endplate 404. The body portion 212 furtherincludes fourth gap 418 between the bottom side portion 410 and thesecond side portion 229, which is sized to receive at least a portion ofthe fourth endplate 406.

The first end 224 of the body portion 212, in an exemplary embodiment,includes an opening 420. The opening 420 extends from the first end 224of the body portion 212 into a central opening 422. In one embodiment,the central opening 422 is sized to receive the translation member 218.The second end 226 of the body portion 212, in an exemplary embodiment,includes an opening 236, which extends from the second end 226 of thebody portion 212 into the central opening 422.

Although the following discussion relates to the first endplate 400, itshould be understood that it also equally applies to the second endplate402, the third endplate 404, and the fourth endplate 406, as theseendplates 402, 404, 406 are substantially identical to the firstendplate 400 in embodiments of the present invention. Turning now toFIGS. 28-30, in an exemplary embodiment, the first endplate 14 has afirst end 424 and a second end 426. The first endplate further includesan upper surface 240 connecting the first end 424 and the second end 426and a lower surface 242 on an opposing side of the endplate 400connecting the first end 424 and the second end 426. While notillustrated, the first endplate 214 may include a through opening sizedto receive bone graft or similar bone growth inducing material andfurther allow the bone graft or similar bone growth inducing material tobe packed in the central opening 422 in the body portion 212.

In one embodiment, the lower surface 242 includes at least one firstretaining socket 428 on the lower surface 242. In an exemplaryembodiment, the lower surface 242 includes a first retaining socket 428at the interior corner of the intersection of the first end 424 and thelower surface 242, and a second retaining socket 430 at the interiorcorner of the intersection of the first end 424 and the lower surface242.

Referring now to FIGS. 28-30, in one embodiment, the upper surface 240of the first endplate 400 is curved convexly. Alternatively, the uppersurface 240 is flat or curved concavely to allow for a greater or lesserdegree of engagement with the adjacent vertebral body 2 (shown on FIG.1, for example). It is also contemplated that the upper surface 240 canbe generally planar but includes a generally straight ramped surface ora curved ramped surface. The ramped surface allows for engagement withthe adjacent vertebral body 2 in a lordotic fashion. In an exemplaryembodiment, the upper surface 240 includes texturing 250 to aid ingripping the adjacent vertebral bodies. Although not limited to thefollowing, the texturing can include teeth, ridges, friction increasingelements, keels, or gripping or purchasing projections.

With reference to FIG. 28, in an exemplary embodiment, the translationmember 218 is sized to be received within the central opening 422 of thebody portion 212. The translation member 218 should be sized to allowlongitudinal translation within the central opening 422. In anembodiment, the translation member 218 includes at least a firstexpansion portion 252. In another embodiment, the translation member 218includes a first expansion portion 252 and a second expansion portion254, the expansion portions 252, 254 being connected together via abridge portion 256. It is also contemplated that there may be more thantwo expansion portions where each of the expansion portions is connectedby a bridge portion. The expansion portions 252, 254 each have angledsurfaces 258, 260. In an embodiment, the angles surfaces 258, 260 eachcomprise first end 229 and second end 231 with second end 231 beingwider than the first end 229. In an exemplary embodiment, the expansionportions 252, 254 include grooved portions 432, 434 on the edges of atleast two sides (e.g., the lateral sides) of the angled surfaces 258,260. The grooved portions 432, 434 are configured and dimensioned toengage the first and second retaining sockets 428, 430 on the endplates400, 402, 404, 406. In an exemplary embodiment, the grooved portions432, 434 retain the first and second retaining sockets 428, 430 insliding engagement.

In one embodiment, the translation member 218 includes a first end 436and a second end 438. The first end 436 of the translation memberincludes an extension 440 sized to be received within the opening 420 inthe first end 224 of the body portion 212. While not illustrated, thesecond end 438 also can include a similar extension sized to be receivedwithin opening 232 in the second end 226 of the body portion 212.

The expandable fusion device 210 of FIGS. 28-30 can be inserted into theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 15-19. After insertion, the expandablefusion device 210 of FIGS. 28-30 can be expanded into the expandedposition. As previously mentioned, the fusion device 210 shown on FIGS.28-30 expands both vertically and laterally. To expand the fusion device210, the translation member 218 can be moved with respect to the bodyportion 212 toward the first end 224 of the body portion. An instrumentcan be used, in an exemplary embodiment. As the translation member 218moves, the first retaining socket 428 and the second retaining socket430 ride along the grooved portions 432, 434 of the expansion portions252, 254 pushing the endplates 400, 402, 404, 406 outwardly in thedirection indicated by arrows 442. In an embodiment, the endplates 400,402, 404, 406 move outwardly in an oblique fashion to expand the fusiondevice 210 both vertically and laterally. The expanded configuration ofthe expansion device 210 is best seen in FIG. 30.

After expansion, the expandable fusion device 210 can be contracted backto the unexpanded configuration. The unexpanded configuration of thefusion device 210 is best seen in FIG. 29. To contract the fusion device210, the translation member 218 is moved with respect to the bodyportion 212 toward the second end 226 of the body portion 212. As thetranslation member 218 moves, the first retaining socket 428 and thesecond retaining socket 430 ride along the grooved portions 432, 434 ofthe expansion portions 252, 254 pulling the endplates 400, 402, 404, 406inwardly in a direction opposite that indicated by arrows 442. In anembodiment, the endplates 400, 402, 404, 406 move inwardly in an obliquefashion to contract the fusion device 210 both vertically and laterally.

With reference to FIGS. 31-32, another embodiment of expandable fusiondevice 210 is shown. In an exemplary embodiment, the fusion device 210includes a body portion 212, a vertically expanding plate 500, and agear 502. In this embodiment, a portion of the fusion device 210 isconfigured to expand vertically in at least one direction. In anexemplary embodiment, the vertically expanding plate 500 is configuredto expand outwardly from the body portion 212. It is contemplated thatan expandable fusion device 210 may be used to correct spinal curvaturedue to, for example, scoliosis, lordosis, and the like.

In an exemplary embodiment, the body portion 212 has a first end 224, asecond end 226, a first side portion 228 connecting the first end 224and the second end 226, and a second side portion 229 on the opposingside of the body portion 212 connecting the first end 224 and the secondend 226. The first end 224 of the body portion 212, in an exemplaryembodiment, includes at least one angled surface 234, but can includemultiple angled surfaces. The angled surface 234 can serve to distractthe adjacent vertebral bodies when the fusion device 210 is insertedinto an intervertebral space. In another preferred embodiment, it iscontemplated that there are at least two opposing angled surfacesforming a generally wedge shaped to distract the adjacent vertebralbodies when the fusion device 210 is inserted into an intervertebralspace. In yet another preferred embodiment, first side portion 228 andsecond side portion 229 each include a recess 238 located towards thesecond end 226 of the body portion 212. The recess 238 is configured anddimensioned to receive an insertion instrument 504 that assists in theinsertion of the fusion device 210 into an intervertebral space.

In an exemplary embodiment, the body portion 212 includes an upperengagement surface 506 extending from the first end 224 towards thesecond end 226, and a lower engagement surface 508 extending between thefirst end 24 and the second end 26. In an embodiment, the upperengagement surface 506 has a through opening 510. Although notillustrated, the lower engagement surface 508 may have a through openingthat is similar to through opening 510. The through opening 510, in anexemplary embodiment, is sized to receive bone graft or similar bonegrowth inducing material and further allow the bone graft or similarbone growth inducing material to be packed in the central opening in thebody portion 212. In an embodiment, at least a portion of the bodyportion 212 is removed to form a landing 512 in the body portion 212. Inan exemplary embodiment, a portion of the upper engagement surface 506and the second end 226 are removed to form the landing 512 having anupper surface 514. While not illustrated, a portion of the lowerengagement surface 508 and the second end 226 may be cut away, in analternative embodiment, to form the landing 512.

In one embodiment, the upper engagement surface 506 and the lowerengagement surface 508 are flat and generally planar to allow engagementsurfaces 506 to engage with the adjacent vertebral body 2 (shown on FIG.34, for example) and the lower engagement surface 508 to engage with theadjacent vertebral body 3 (shown on FIG. 34, for example).Alternatively, the upper engagement surface 506 and/or the lowerengagement surface 508 can be curved convexly or concavely to allow fora greater or lesser degree of engagement with the adjacent vertebralbodies 2, 3. In an exemplary embodiment, the upper engagement surface506 and/or the lower engagement surface includes texturing 512 to aid ingripping the adjacent vertebral bodies. Although not limited to thefollowing, the texturing can include teeth, ridges, friction increasingelements, keels, or gripping or purchasing projections.

In an exemplary embodiment, vertically expanding plate 500 is coupled toan end of threaded bolt 518, which is coupled to the gear 502. In oneembodiment, the threaded bolt 518 is in threaded engagement with thegear 502. In an alternative embodiment, a bolt having ratchet teeth maybe used instead of threaded bolt 518. In an embodiment, the gear 502 iscoupled to the landing 512. In one embodiment, the gear 502 is rotatablycoupled to the landing 512.

The vertically expanding plate 500 includes a through bore 519 and anupper surface 520. In one embodiment, the vertically expanding plate 500is generally circular in shape. Other suitable configurations of theexpanding plate 500 may also be suitable. In an embodiment, thevertically expanding plate may be generally rectangular in shape withrounded corners, as best seen in FIG. 33. In one embodiment, thevertically expanding plate 500 is flat and generally planar to allowupper surface 520 to engage with the adjacent vertebral body 2.Alternatively, the upper surface 520 can be curved convexly or concavelyto allow for a greater or lesser degree of engagement with the adjacentvertebral bodies. In an exemplary embodiment, the upper surface 520includes texturing 522 to aid in gripping the adjacent vertebral bodies.Although not limited to the following, the texturing can include teeth,ridges, friction increasing elements, keels, or gripping or purchasingprojections.

With reference to FIG. 33, an alternative embodiment of the expandablefusion device 210 of FIGS. 31-32 is shown. In this embodiment, the gear502 is enclosed within the body portion 212 towards the second end 226of the body portion 212 with the vertically expanding plate 500 disposedat or above the upper engagement surface 506 of the body portion 212. Inan embodiment, the vertically expanding plate 500 is positioned towardsthe second end 226 of the body portion 212. While not illustrated, thethreaded bolt 518 extends through the upper engagement surface 506 andcouples the vertically expanding plate 500 and the gear 502. An actuatorscrew 524 extends through the first end 224 of the body portion 212 toengage the gear 502.

The expandable fusion device 210 of FIGS. 31-33 can be inserted in theintervertebral space in a manner similar to that the previouslydescribed with respect to FIGS. 15-19. FIG. 34 illustrates theexpandable fusion device 210 of FIG. 33 between adjacent vertebralbodies 3, 4 in an unexpanded position. After insertion, the expandablefusion device 210 of FIGS. 31-33 can be expanded into the expandedposition. As previously mentioned, a portion of the fusion device shownon FIGS. 31-33 expands vertically in at least one direction. Topartially expand the fusion device 210, the gear 502 can be rotated in afirst direction. An instrument 526 having a gear 528 disposed on adistal end 530 of the instrument may be used to rotate the gear 502, asbest seen on FIG. 32. In another embodiment, an instrument (notillustrated) may be used to rotate actuation member 524 in a firstdirection. As discussed above, the actuation member 524 is engaged withgear 502; thus, as the actuation member 524 is rotated in firstdirection, the gear 502 rotated in a first direction. The embodimentwith the actuation member 524 is best seen in FIG. 33. As the gear 502rotates, the threaded bolt 518 extends outward from the gear 502, thusextending the laterally expanding plate 500 outward from the bodyportion 212. FIG. 35 illustrates the expandable fusion device 210 ofFIG. 33 in an expanded position.

After expansion, the expandable fusion device 210 can be contracted backto the unexpanded position. The unexpanded position of the fusion device210 is best seen in FIG. 34. To contract the fusion device 210, the gear502 is rotated in a second direction that is opposite the firstdirection. The instrument 526 with the gear 528 may be used to rotatethe gear 502. Alternatively, an instrument may be used to rotate theactuation member 524 to turn the gear 502 in the second direction. Asthe gear 502 rotates in the second direction, the threaded bolt 518retracts pulling the laterally expanding plate 500 inward into theunexpanded position.

With reference now to FIGS. 36 and 37, an alternative embodiment of anexpandable fusion device 600 is shown. In an exemplary embodiment, theexpandable fusion device 600 includes a body portion 602, an expandablemember 604, a ramped translation member 606, and an actuation member608. In accordance with present embodiments, the expandable fusiondevice 600 is configured for angled expansion (also referred to hereinas “lordotic” expansion). Angled expansion of the expandable fusiondevice 600 may beneficial, for example, to introduce or even increaselordosis in the spine. By increasing lordosis, saggital balance may berestored, in some embodiments.

With additional reference to FIGS. 38-41 and 43, the body portion 602will now be described in more detail in accordance with exampleembodiments. As illustrated, the body portion 602 has an anterior end610 and a posterior end 612. A first side portion 614 and a second sideportion 616 may connect the anterior end 610 and the posterior end 612.As best seen on FIG. 43, the body portion 602 may be generally hollowwith the anterior end 610, the posterior end 612, the first side portion614, and the second side portion 616 defining an internal cavity 618that has an upper window 620 and a lower window (not shown). In oneembodiment, the internal cavity 618 is sized to receive the expandablemember 604.

The anterior end 610 of the body portion 602, in an exemplaryembodiment, includes one or more angled surfaces 622, but can includemultiple angled surfaces. The angled surfaces 622 can serve to distractadjacent vertebral bodies 3, 4 (e.g., shown on FIG. 1) when the fusiondevice 600 is inserted into intervertebral spaces. In another preferredembodiment, it is contemplated that there at least two opposing angledsurfaces 622 forming a generally wedge shape to distract the adjacentvertebral bodies when the fusion device 10 is inserted into anintervertebral space.

The posterior end 612 of the body portion 602, in an exemplaryembodiment, includes an opening 623, such as a cylindrical bore, forexample. The opening 623 may extend from the posterior end 612 into theinternal cavity 618 in the body portion 602. In one embodiment, theopening 623 is sized to receive the actuation member 608. The opening623 may include a mechanical stop 632 (e.g., a rim, lip, etc.)projecting from an internal surface 634 of the opening. The internalsurface 634 may further include an internal groove 636 spacedposteriorly from the mechanical stop 632. In another embodiment, thefirst and second side portions 614, 616 each include a recess 624located at or near the posterior end 612 of the body portion 602. Therecess 624 may be configured and dimensioned to receive an insertioninstrument (not shown) that assists in the insertion of the fusiondevice 600 into an intervertebral space.

The posterior end 612 of the body portion 602, in an exemplaryembodiment, further includes upper and lower bone engagement surfaces626, 628 at the posterior end 612. The upper and lower bone engagementsurfaces 626, 628 may be configured to engage the adjacent vertebralbodies 2, 3 (shown on FIG. 1, for example). In the illustratedembodiment, the upper and lower bone engagement surfaces 626, 628 eachinclude texturing 630 to aid in gripping the adjacent vertebral bodies2, 3. Although not limited to the following, the texturing can includeteeth, ridges, friction increasing elements, keels, or gripping orpurchasing projections.

With reference now to FIGS. 36-42, the expandable member 604 will now bedescribed in more detail in accordance with example embodiments. It iscontemplated that the expandable member 604 can be made from a flexiblematerial, such as PEEK, or any other biocompatible material such asstainless steel or titanium. However, other materials may also be usedfor the expandable member 604 in accordance with embodiments of thepresent invention. As illustrated, the expandable member 604 may includetwo or more arms, such as first arm 638 and second arm 640, separated bya channel 642. The expandable member 604 may further include a fixed end644 and an expandable end 646 with the channel 642 running between thefirst and second arms 638, 640 from the fixed end 644 to the expandableend 646. The first arm 638 and the second arm 640 may be connected atthe fixed end 644 which links the first and second arms 638, 640. Thefirst and second arms 638, 640 may move substantially independent fromone another at the expandable end 646 while remaining connected at thefixed end 644. As illustrated, the first and second arms 638, 640 may beseparated by the channel 642. In the illustrated embodiment, the channel642 ends at the fixed end 644 in a slightly larger diameter which acts ahinge during expansion of the fusion device 600. Markers 658 (FIG. 36)may be seated in recesses (such as blind holes 660 shown on FIG. 42)formed in each of the first and second arms 638, 640 to, for example, toassist in imaging of the device, such as fluoroscopy. In addition, theexpandable member 604 may also include a posterior opening 662 in thefixed end 644, such as a cylindrical bore, through which the actuationmember 608 can extend, as best seen in FIGS. 39 and 41.

As best seen in FIGS. 39, 41, and 42, the first and second arms 638, 640of the expandable member 604 each include ramped surfaces 648, 650,respectively. In the illustrated embodiment, the ramped surfaces 648,650 are at or near the expandable end 646. In the illustratedembodiment, the first and second arms 638 each include one rampedsurface (e.g., ramped surface 648 and ramped surface 650), but caninclude any number of ramped surfaces.

In the illustrated embodiment, the first and second arms 638, 640 eachinclude bone engagement surfaces 652, 654, respectively, that faceoutward. As illustrated, the bone engagement surfaces 652, 654 may beflat and generally planar to allow for engagement of the first andsecond arms 638 with the adjacent vertebral bodies 3, 4 (e.g., shown onFIG. 1). Alternatively (not illustrated), the bone engagement surfaces652, 654 may be curved convexly or concavely to allow for a greater orless degree of engagement with the adjacent vertebral bodies 3, 4. Italso contemplated that the bone engagement surfaces 652, 654 may begenerally planar, but include a generally straight ramped or a curvedramped surface. The ramped surface may allow for an even greater degreeof angled expansion. In some embodiments, the bone engagement surfaces652, 654 may include texturing 656 to aid in gripping the adjacentvertebral bodies 3, 4. Although not limited to the following, thetexturing can include teeth, ridges, friction increasing elements,keels, or gripping or purchasing projections.

With reference now to FIGS. 36, 39, and 41, the ramped translationmember 606 will now be described in more detail in accordance withexample embodiments. As illustrated, the ramped translation member 606includes a first expansion portion 664 and a second expansion portion666, the first and second expansion portions 664, 666 being connected byone or more bridge portions 668. It is also contemplated that there maybe more than two expansion portions. The first expansion portion 664 mayhave ramped surfaces 670, 672, which may be dimensioned and configuredto engage the ramped surfaces 648, 650 in the expandable end 646 of theexpansion member 604. In the illustrated embodiment, the first expansionportion 664 includes two ramped surfaces 670, 672. In the illustratedembodiment, the ramped surfaces 670, 672 of the first expansion portion664 are rear facing. With additional reference to FIGS. 37 and 43, anembodiment further includes one or more screws 674 that are received inthe first expansion portion 664 with the screws 674 being threadedthrough openings 676 in the posterior end 612 of the body portion 602 tostabilize the ramped translation member 606 in the internal cavity 618of the body portion 602. The ramped translation member 606, in anexemplary embodiment, may further include an opening 680, such as acylindrical bore, sized to receive the actuation member 608. In theillustrated embodiment, the opening 680 is disposed in the secondexpansion portion 666.

With reference to FIGS. 36, 39, and 41, the actuation member 608 willnow be described in more detail in accordance with example embodiments.In an exemplary embodiment, the actuation member 608 has a first end 682and a second end 684. As illustrated, the actuation member 608 mayinclude a head portion 686 at the second end 684 and a extension portion688 extending from the head portion. Threading 690 disposed on theextension portion 688 should threadingly engage corresponding threading692 along a portion of the opening 680 of the ramped translation member606. In another embodiment (not shown), the actuation member 608 mayinclude ratchet teeth instead of the threading 690 with the ratchetteach engaging corresponding ratchet teeth in the opening 680 of theramped translation member 606. The second end 684 includes a recess 694dimensioned to receive an instrument (not shown) that is capable ofrotating or otherwise moving the actuation member 608.

As illustrated, the head portion 686 of the actuation member 608 mayfurther include a flange 696 or other suitable projection. In someembodiments, the flange 696 of the actuation member 608 may engage themechanical stop 632 projecting from the interior surface 634 of theopening 623 in the body portion 602. Engagement of the flange 696 withthe mechanical stop 632 may restrict forward movement of the actuationmember 608 into the opening 623 in the body portion 602. As illustrated,a ring 698 (e.g., a PEEK ring) may be disposed between the mechanicalstop 632 and the flange 696 to reduce friction between the actuationmember 608 and the body portion 602, for example, when the fusion device600 is actuated, such as by rotation of the actuation member 608, forexample. As further illustrated, a retaining ring 699 may be used toengage the head portion 686 and hold the actuation member 608 in theopening 623 in the body portion 602, for example, preventing threadingout of the actuation member 608 when rotated. The retaining ring 699 maybe disposed in the internal groove 636 in the opening 623 of the bodyportion 602, for example. In one embodiment, the retaining ring 699 maybe a snap ring.

Turning now to FIGS. 36-41, an example method of installing theexpandable fusion device 600 is now discussed. Prior to insertion of thefusion device 600, the intervertebral space is prepared. In one methodof installation, a diskectomy is performed where the intervertebraldisc, in its entirety, is removed. Alternatively, only a portion of theintervertebral disc can be removed. The endplates of the adjacentvertebral bodies 2, 3 (shown on FIG. 1, for example) are then scraped tocreate an exposed end surface for facilitating bone growth across theintervertebral space. The expandable fusion device 600 is thenintroduced into the intervertebral space, with the anterior end 610 ofthe body portion 602 being inserted first into the disc space followedby the posterior end 612. In an exemplary method, the fusion device 600is in the unexpanded position when introduced into the intervertebralspace. The wedged-shaped of the anterior end 610 in the illustratedembodiment should assist in distracting the adjacent vertebral bodies 2,3, if necessary. This allows for the option of having little to nodistraction of the intervertebral space prior to the insertion of thefusion device 600. In another exemplary method, the intervertebral spacemay be distracted prior to insertion of the fusion device 600. Thedistraction provide some benefits by providing greater access to thesurgical site making removal of the intervertebral disc easier andmaking scraping of the endplates of the vertebral bodies 2, 3 easier.

With the fusion device 600 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device 600 canthen be expanded into the expanded position, as best seen in FIGS.38-41. FIGS. 38 and 39 show the fusion device 600 prior to expansionwhile FIGS. 40 and 41 show the fusion device 600 in the expandedposition. To expand the fusion device 600, an instrument is engaged withthe recess 694 in the second end 684 of the actuation member 608. Theinstrument is used to rotate actuation member 608. As discussed above,actuation member 608 can be engaged (e.g., threadingly engaged) with theramped translation member 606; thus, as the actuation member 608 isrotated in a first direction, the ramped translation member 606 moveswith respect to the body portion 602 toward the posterior end 612 of thebody portion 602. In another exemplary embodiment, the rampedtranslation member 606 is moved in a linear direction with the ratchetteeth engaging as means for controlling the movement of the rampedtranslation member 606. As the ramped translation member 606 moves, theramped surfaces 670, 672 of the first expansion portion 664 push againstthe ramped surfaces 648, 650 in the expandable end 646 of the expandablemember 604 pushing the first and second arms 638, 640 outwardly into theexpanded position. This can best be seen in FIGS. 40 and 41. Since theexpansion of the fusion device 600 is actuated by a rotational input,the expansion of the fusion device 600 is infinite. In other words, thefirst and second arms 638, 640 can be expanded to an infinite number ofheights dependent on the rotational advancement of the actuation member608.

In the event the fusion device 600 needs to be repositioned or revisedafter being installed and expanded, the fusion device 600 can becontracted back to the unexpanded configuration, repositioned, andexpanded again once the desired positioning is achieved. To contract thefusion device 600, the instrument is engaged with the recess 694 in thesecond end 684 of the actuation member 608. The instrument is used torotate actuation member 608. As discussed above, actuation member 608can be threadingly engaging the ramped translation member 606; thus, asthe actuation member 608 is rotated in a second direction, opposite thefirst direction, the ramped translation member 606 moves with respect tothe body portion 602 toward the anterior end 610 of the body portion602. As the ramped translation member 606 moves, the first and secondarms 638, 640 should contract inwardly back into their unexpandedposition, for example.

With continued reference to FIGS. 36-41, an example method of assemblythe expandable fusion device 600 is now discussed. In accordance withpresent embodiments, the ramped translation member 606 may be insertedinto the expandable member 604. By way of example, the second expansionportion 666 may be inserted into the channel 642 of the expandablemember 604 at the expandable end 646 and advanced to the fixed end 644.After insertion of the ramped translation member 606, the expandablemember 604 may then be placed into the internal cavity 618 in the bodyportion 602. For example, the expandable member 604 may be insertedthrough window (e.g., upper window 620) into the internal cavity 618. Asillustrated, the fixed end 644 of the expandable member 604 should bepositioned near the posterior end 612 of the body portion 602. The oneor more screws 674 may then be inserted through the body portion 602 andinto the ramped translation member 606 to, for example, stabilize theramped translation member 606 preventing rotation. The actuation member608 may also be inserted into the opening 623 in the posterior end 612of the body portion and advanced until it is in engagement with theramped translation member 606. In one embodiment, the actuation member608 may be advanced into threaded engagement with the opening 680 in theramped translation member.

In an embodiment, the expandable fusion device 600 can be configured andsized to be placed into an intervertebral disc space between theadjacent vertebral bodies 2 and 3 (shown on FIG. 1, for example) andexpanded. In some embodiments, the expandable fusion device 600 may havea width in a range of from about 8 mm to about 22 mm and a length in arange of from about 15 mm to about 65 mm. In further embodiments, theexpandable fusion device 600 may have a width in a range of from about 8mm to about 12 mm and a length in a range of from about 20 mm to about30 mm. In some embodiments, the expandable fusion device 10 may have aninitial height in an unexpanded position in a range of from about 7 mmto about 20 mm and, alternatively from about 7 mm to about 15 mm. Insome embodiments, the maximum expansion of the first and second arms638, 640 at the anterior end 610 of the body portion 602 is about 4 mmor potentially even more.

FIGS. 44 and 45 illustrate an alternative embodiment of the expandablefusion device 600 according to the present invention. For longerconfigurations of the expandable fusion device 600, the first and secondarms 638, 640 may sag or flex, for example, when engaging the adjacentvertebral bodies 3, 4 (shown on FIG. 1, for example). Accordingly,embodiments shown on FIGS. 44 and 45 further include one or moreprotruding support members 700 on the ramped translation member 606. Asillustrated, the protruding support members 700 may be disposed on theone or more of the bridge portions 668 between the first and secondexpansion portions 664, 666. The protruding support members 700 mayengage corresponding recesses 702 in the first and second arms 638, 640.The protruding support members 700 may act to support the first andsecond arms 638, 640 and prevent undesired flexing during expansion. Inalternative embodiments (not shown), the actuation member 608 may engagethe expandable member 604 (for example, with a slot and a groove) sothat, as the first and second arms 638, 640 expands, the actuationmember 608 may engage the expandable member 604 to cause convexity.

FIG. 46 illustrates an alternative embodiment of the expandable fusiondevice 600 according to the present invention. The embodimentsillustrated on FIGS. 36-42 illustrate the ramped surfaces 670, 672 onthe first expansion portion 664 of the ramped translation member 606being rear facing. In the embodiment illustrated on FIG. 46, the rampshave been reversed with the ramped surfaces 670, 672 on the firstexpansion portion 664 being forward facing. Accordingly, thecorresponding ramped surfaces 648, 650 on the first and second arms 638,640 of the expandable member 604 have also been reversed and are shownon FIG. 46 as being rear facing. Accordingly, rotation of the actuationmember 608 should move the ramped translation member 606 forward to theanterior end 610 of the body portion 602 such that the ramped surfaces670, 672 of the ramped translation member 606 push against the rampedsurfaces 648, 650 of the first and second arms 638, 640 pushing thefirst and second arms 638, 640 outwardly into the expanded position.

As previously mentioned, embodiments of the expandable fusion devices,such as expandable fusion device 600 shown on FIGS. 36-42 in which theendplates (e.g., endplates 14, 16 or first and second arms 638, 640) mayexpand into an angled configuration. As illustrated by FIGS. 47-58, theendplates 704, 706 of an expandable fusion device 600 may be expanded ina number of different ways. For example, FIGS. 47-49 illustrate anexpandable fusion device 600 in which the endplates 704, 706 only expandat the anterior side 708 while remaining fixed at the posterior side710. FIGS. 50-52 illustrate an additional example of an expandablefusion device 600 in which the endplates 704, 706 expand at both theanterior side 708 and the posterior side 710 but at different rates.FIGS. 53-55 illustrate yet another example of an expandable fusiondevice 600 in which the endplates 704, 706 first expand at only theanterior side 708 to achieve lordotic angle followed by expansion atboth the anterior side 708 and the posterior side 710 at constant ratesto achieve height increase. Advantageously, the embodiment shown onFIGS. 53-55 allows for full angulation without the corresponding heightincrease. FIGS. 56-58 illustrate yet another example of an expandablefusion device 600. As illustrated, the expandable fusion device 600 hastwo separate degrees of freedom, allowing for independent angulation andexpansion of the endplates 704, 706.

Although the preceding discussion only discussed having a single fusiondevice (e.g., fusion device 10, fusion device 210, or fusion device 600)in the intervertebral space, it is contemplated that more than onefusion device can be inserted in the intervertebral space. It is furthercontemplated that each fusion device does not have to be finallyinstalled in the fully expanded state. Rather, depending on the locationof the fusion device in the intervertebral disc space, the height of thefusion device may vary from unexpanded to fully expanded.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims. Althoughindividual embodiments are discussed, the invention covers allcombinations of all those embodiments.

What is claimed is:
 1. An intervertebral implant comprising: a bodyportion comprising an anterior end, a posterior end, a first sideportion connecting the anterior end and the posterior end, and a secondside portion connecting the anterior end and the posterior end, theanterior end, posterior end, first side portion and second side portiondefining a central opening; an expandable member comprising a fixed end,an expandable end, a first arm, and a second arm, the first arm and thesecond arm being connected at the fixed end, the first arm and thesecond arm being moveable with respect to one another at the expandableend, wherein at least a portion of the expandable member is receivedwithin the central opening of the body portion; a ramped translationmember having at least one expansion portion, at least a portion of thetranslation member is received within the central opening, at least aportion of the ramped translation member being received within a channeldefined between the first arm and the second arm of the expandablemember; and an actuation member in engagement with the rampedtranslation member.
 2. The intervertebral implant of claim 1, whereinmovement of the ramped translation member in a first direction causesthe first and second arms to move outwardly at the expandable end of theexpandable member while the first and second arms remain fixed at thefixed end.
 3. The intervertebral implant of claim 2, wherein rotationalmovement of the actuation member causes the ramped translation member tomove linearly in the first direction.
 4. The intervertebral implant ofclaim 2, wherein the first arm comprises a ramped surface, wherein thesecond arm comprises a ramped surface, wherein the at least oneexpansion portion comprises a first ramped surface and a second rampedsurface, wherein the first ramped surface abuts against the rampedsurface of the first arm, and wherein the movement of the rampedtranslation member in the first direction causes the first rampedsurface of the at least one expansion portion to push against the rampedsurface of the first arm and the second ramped surface of the at leastone expansion portion to push against the ramped surface of the secondarm.
 5. The intervertebral implant of claim 1, wherein the anterior endof the body portion comprises angled surfaces for distracting vertebralbodies.
 6. The intervertebral implant of claim 1, wherein the posteriorend of the body portion comprises an opening for receiving the actuationmember.
 7. The intervertebral implant of claim 1, wherein the first andsecond side portions comprise a recess configured and dimensioned forreceiving an insertion instrument.
 8. The intervertebral implant ofclaim 1, wherein the posterior end of the body portion comprises upperand lower bone engagement surfaces that each comprise texturing forgripping vertebral bodies.
 9. The intervertebral implant of claim 1,wherein the expandable member is made from a material comprisingpolyether ether ketone.
 10. The intervertebral implant of claim 1,wherein the first and second arms each comprise outwardly facing boneengagement surfaces that each comprise texturing for gripping vertebralbodies.
 11. The intervertebral implant of claim 1, wherein the at leastone expansion portion of the ramped expansion member comprises a firstexpansion portion comprising one or more ramped surfaces for engagingcorresponding ramped surfaces on the first and second arms, and a secondexpansion portion in engagement with the actuation member, the firstexpansion portion and the second expansion portion being connected by abridge portion.
 12. The intervertebral implant of claim 11, wherein thebridge portion comprises one or more protruding support members, theprotruding support members each being in engagement with a correspondingrecess in the first arm or the second arm.
 13. The intervertebralimplant of claim 11, wherein the second expansion portion comprises anopening sized to receive the actuation member.
 14. The intervertebralimplant of claim 11, wherein one or more screws are disposed through theanterior end of the body portion and into the first expansion portion ofthe ramped expansion member.
 15. The intervertebral implant of claim 1,wherein the actuation member comprises a head portion and an extensionportion from the head portion, the extension portion comprisingthreading, the actuation member being in threaded engagement with theramped translation member.
 16. The intervertebral implant of claim 15,wherein the actuation member is received within an opening in theposterior end of the body portion, the opening including a mechanicalstop that limits forward movement of the actuation member into theopening.
 17. The intervertebral implant of claim 16, wherein a ring isdisposed between the head portion of the actuation member of themechanical stop.
 18. The intervertebral implant of claim 17, wherein aretaining ring disposed in groove in the opening of the body portionengages the head portion of the actuation member on the opposite side ofthe ring.
 19. A method of installing an intervertebral implant, themethod comprising: positioning the intervertebral implant betweenadjacent vertebrae, the intervertebral implant having a body portionwith an anterior end and a posterior end, the anterior end beinginserted first into the disc space followed by the posterior end; androtating an actuation member of the implant in a first direction, therotation of the actuation member causes a ramped translation member ofthe implant to move in a first linear direction, the translation memberhaving at least one expansion portion comprising two ramped surfaces,each of the ramped surfaces pushing against one or more ramped surfaceson a first arm or a second arm of an expandable member of theintervertebral implant causing the first arm and the second arm to moveoutwardly at an expandable end of the expandable member while the firstarm and the second arm remain fixed at a fixed end of the expandablemember, the first arm and the second arm being connected at the fixedend.
 20. The method of installing the intervertebral implant of claim19, the method further comprising: rotating the actuation member of theimplant in a second direction, the second direction being opposite thefirst direction, the rotation of the actuation member causes the rampedtranslation member to move in a second linear direction opposite thefirst linear direction, wherein the first arm and the second armcontract inward as the ramped translation member moves in the secondlinear direction.
 21. A method of assembling an intervertebral implant,the method comprising: providing an expandable member, the expandablemember comprising a fixed end, an expandable end, a first arm, and asecond arm, the first arm and the second arm being connected at thefixed end, the first arm and the second arm being moveable with respectto one another at the expandable end; inserting a ramped translationmember into a channel formed between the first arm and the second arm ofthe expandable member; inserting the expandable member into a centralopening of a body portion, the body portion comprising an anterior end,a posterior end, a first side portion connecting the anterior end andthe posterior end, and a second side portion connecting the anterior endand the posterior end, the anterior end, posterior end, first sideportion and second side portion defining the central opening; andinserting an actuation member into an opening in the posterior end ofthe body portion to engage the ramped translation member.
 22. The methodof claim 21, further comprising inserting one or more screws through theanterior end of the body portion to engage the ramped translationmember.